Automobile exhaust muffler

ABSTRACT

An exhaust gas muffler comprises a housing containing a pair of laterally spaced exhaust conduits opening into a transverse turnaround passage within the housing for conducting exhaust gas transversely from one conduit to the other. A portion of the turnaround passage laterally of the openings of the conduits thereinto comprises a high frequency tuning chamber separated from the remainder of the turnaround passage by a partition perforated to provide an acoustical coupling between the two portions of the turnaround passage to attenuate high frequency sound waves in the exhaust gas.

United States Patent Inventor Appl, No.

Filed Patented Assignee Darwin E. Grote Howell, Mich.

Dec. 22, 1969 Jan. 26, 1971 Chrysler Corporation Highland Park, Mich.

a corporation 01' Delaware AUTOMOBILE EXHAUST MUFFLER 8 Claims, 3 Drawing Figs.

US. Cl 181/54, 181/61 Int. Cl .1 F0ln 1/08, FOln 7/18 Field ofSearch 181/48, 54,

[56] References Cited UNITED STATES PATENTS 2,109,220 2/1938 Noblitt et a1 181/54 2,182,945 12/1939 Gunn 181/33(.04)

Primary Examiner-Robert S. Ward, Jr. Attorneyl-Iarness, Talburtt and Baldwin ABSTRACT: An exhaust gas muffler comprises a housing containing a pair of laterally spaced exhaust conduits opening into a transverse turnaround passage within the housing for conducting exhaust gas transversely from one conduit to the other. A portion of the turnaround passage laterally of the openings of the conduits thereinto comprises a high frequency tuning chamber separated from the remainder of the turnaround passage by a partition perforated to provide an acoustical coupling between the two portions of the turnaround passage to attenuate high frequency sound waves in the exhaust gas.

AUTOMOBILE EXHAUST MUFFLER BACKGROUND AND SUMMARY OF THE INVENTION In a conventional multiple pass muffler for the exhaust gases of an automobile engine, an outer sheet metal housing encloses a space of generally oval transverse cross section through which the exhaust gases pass in a convoluted path. For example in a three-pass muffler, a forward exhaust pipe section conducts the gases from the engine exhaust manifold and through the front end of the housing into a transverse rear turnaround passage, wherein the gases flow transversely to a return flow exhaust pipe section parallel to and spaced from the forward pipe section. The return pipe section conducts the exhaust gases forwardly to a transverse front turnaround passage, wherein the gases again flow transversely to a tailpipe section parallel to and spaced from both of the other pipe sections. The tailpipe section then conducts the gases rearwardly through the rear end of the housing and discharges to atmosphere.

The turnaround passages are formed within the housing by transverse sheet metal baffles, usually in cooperation with one or both endwalls of the housing, which extend from side to side and top to bottom within the housing to reinforce the latter and support the exhaust pipe sections. Sound attenuating means comprise openings within the exhaust pipe sections communicating with the major dead spaces within the housing. The openings and dead spaces cooperate to resonate out of phase with sound waves in the exhaust gases flow and thereby to muffle or damp these waves and the noise resulting therefrom.

Comparatively high frequency sounds are similarly attenuated, but by means of a sleeve arranged coaxially around one of the pipe sections. The annular space between the sleeve and and pipe section is closed at its ends to comprise a high frequency resonator or tuning chamber and is acoustically coupled with the interior of the coaxial pipe section by a plurality of small resonator openings or louvers. The dimensions of the louvers and tuning chamber are determined in accordance with the frequency of the sound waves to be attenuated. Suolua muffler has been reasonably satisfactory for many years, but :i'tsfull potential for any given size has never been realized.

It is an object of the present invention to provide simple and inexpensive means for improving a muffler of the above character so as to increase its sound damping effectiveness, particularly for higher frequencies, and also to reduce the exhaust back pressure caused by the mufi'ler.

In the turnaround passages, a portion of each adjacent the lateral walls of the housing is substantially unused by the exhaust gas flow. A concept of the present invention is to provide a partition within the turnaround passage to separate its aforesaid unused portion from its active portion, which latter portion conducts the exhaust gas. As a consequence turbulence within the formerly unused portion and impedance to the exhaust flow are reduced. In addition, the formerly unused space between the baffle and sidewall of the housing is now available for use as a high frequency tuning chamber. By forming louvers or resonator openings in the partition to acoustically couple active and formerly unused portions of the turnaround passage, high frequency sounds within the exhaust flow are attenuated.

The resonator thus formed may either supplant the conventional sleeve-type high frequency resonator formerly em ployed, with consequent cost savings and a reduction in the overall dimensions of the muffler, or it may supplement the conventional high frequency resonator for increased muffler efficiency. Furthermore the resonator fonned in accordance with the present invention is advantageously located within the turnaround passage at the region of maximum turbulence and disruption to exhaust gas flow and thus by reason of its location proximate a significant source of high frequency sound is more effective for sound attenuation than is the conventional high frequency resonators located coaxially around an exhaust pipe section remote from the turnaround passage.

Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming apart of this specification wherein like reference characters designate corresponding parts in the several views.

FIG. 1 is a schematic longitudinal sectional view through a muffler embodying the present invention.

FIG. 2 is a sectional view taken in the direction of the arrows substantially along the line 2-2 of FIG. 1.

FIG. 3 is a view similar to FIG. 2, showing a modification.

It is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Referring to the drawings, an embodiment of the present invention is illustrated by way of example in a muffler comprising a conventional sheet metal housing or canister 10 of generally oval section and closed by front and rear sheet metal endwalls 11 and 12 respectively. Three transverse baffle plates 13, 14 and 15 are suitably secured within the housing 10 to provide a front turnaround passage 16 between the endwall 11 and plate 13, a rear turnaround passage 17 between the plates 14 and 15, and a rear resonator chamber 18 between the plate 15 and endwall 12. A cylindrical tuning neck or throat 19 extends axially through the plate 15 from the rear turnaround passage 17 into the chamber 18 and is dimensioned with respect to the volume of the chamber 18 in accordance with conventional practice for attenuating comparatively low frequency sound waves carried by the exhaust gases passing through the muffler.

Exhaust gases are carried through the muffler by three ex haust conduit sections comprising an inlet section 20, a return or reverse flow section 21, and an exhaust section 22. The inlet section 20 is enlarged at its front end 23 to sleeve over an exhaust conduit not shown connected with the exhaust header from the automobile engine. From the forward end 23, the conduit section 20 extends axially into the housing 10 at a lateral location through flanged openings 24 lanced in the front endwall l l and baffle plates 13 and 14. Similarly the tuning neck 19 is secured within a flanged opening 27 lanced in the plate 15. Return section 21 extends axially near the opposite side of the muffler through flanged openings 28 lanced in the plates 13 and 14, and the exhaust section 22 extends through flanged openings 30 lanced in the plates l3, l4, l5, and endwall 12 at locations between the sections 20 and 21. The rear end of the section 22 is enlarged at 34 to provide a sleeve connection with the customary tailpipe section for discharging exhaust to the atmosphere. The assembly of the conduit section, muffler housing, and baffle plates is secured together as for example by welding at the flanged openings in mutually supporting relationship.

The sections 20, 21, and 22 are provided with a plurality of openings or louvers 35 opening radially into a resonator chamber 36 located between the baffles 13 and 14. By suitably determining the size and number of the openings 35 with respect to the volume of the resonator 36, additional muffling of comparatively low frequency sounds is accomplished. It is also customary to provide a sleeve 37 spaced radially from one of the exhaust conduit sections, as for example the section 21, to provide an annular tuning chamber 38 between the sleeve 37 and conduit section 21 cooperable with a plurality of openings or louvers 39 in the section 21 communicating with the space 38 for attenuating comparatively high frequency sounds.

The structure described thus far may be conventional in construction and in operation. Specifically, the exhaust gases from the automobile engine flow through the inlet section 20 into the turnaround passage 17, thence transversely in the latter passage to the return conduit section 21, thence forwardly into the front turnaround passage 16, transversely in the latter passage to the exhaust section 22, and finally in i a.

through the latter conduit section to the atmosphere. A certain amount of short circuiting of the exhaust gas flow between the conduits 20, 21 and 22 via the openings 35 and chamber 36 will result, but this short circuiting is employed for sound attenuation in accordance with customary practice.

Without some provision to the contrary, the region 40 of the turnaround passage 17 for example laterally of the conduit sections 20 and 21 is a source of turbulence and impedance for the gas flow from the section 20 to the section 21. Furthermore this lateral volume 40 in the conventional turnaround passage serves no useful purpose in conducting exhaust gases. In accordance with the present invention, this lateral space 40 is separated from the active or useful central space of the tufnaround passage 17 by a partition 41 extending axially between the plates 14 and 15 and closely around the openings of the conduit sections 20 and 21 into the passage 17, FIG. 2. The space 40 may thus comprise a tuning chamber for comparatively high frequency sounds and is acoustically coupled with the aforementioned active volume of the passage 17 inwardly of the partition 41 by a plurality of openings or louvers 42 dimensioned in accordance with the volume of the space 40 to attenuate such high frequency sounds. I i

Similarly, a comparatively unused space 43 between the baffle 13 and front end 11 is separated from the active volume of the turnaround passage 16 by a partition 44 extending closely around the openings of the conduit sections 21 and 22 into the turnaround passage 16, substantially in the manner of partition 41. Also in the manner of the partition 41, a plurality of openings or louvers 45 are providedin the partition 44 to acoustically couple the volume 43 and passage 16 for attenuating comparatively high frequency sounds in the exhaust gases. The partition 41, instead of comprising a continuous sheet spaced from the sidewalls of the housing 10, FIG. 2, may comprise two separate parts 41' welded at their ends to the housing sidewall 10, FIG. 3.. In accordance with the foregoing, turbulent flow within the turnaround passages 16 and 17 is reduced and sound attenuat ing means for high frequency sounds proximate the regions of maximum turbulence resulting from abrupt changes in the direction of the gas flow between the axial and transverse directions are provided. The high frequency sound attenuation provided by the chambers 40 and 43 may be provided to supplement the sleeve 37 and thereby achieve greater muffler efficiency without increasing the muffler volume, or the spaces-40 and 43 may be employed to replace the sleeve 37, with consequent economy in the construetion'of the mufflefi and also to render a larger portion of the return conduit section 21 available for attenuating lower frequency sounds.

' Iclaim:

1. In a sound attenuating muffler for the exhaust gases of an internal combustion engine,

A. an outer housing,

B. baffle means partitioning said housing to provide a gas flow turnaround passage therein,

C. exhaust conduit means cooperable with said passage for conducting said gases through said housing comprising a pair of conduit sections opening into said passage at spaced locations, at least one of said conduit sections opening into said passage at a location spaced from the interior of said housing to provide a space proximate said interior comparatively unused for conducting said gases through said housing, and l D. means for attenuating comparatively high frequency sounds in said gases comprising:

1. a partition within said passage separating said comparatively unused spacefr'or'n the fl ow'of said gases within an active region of said passage between the openings of said conduit sections into said passage and cooperating with said interior to' define a tuning chamber for said high frequency sounds; and 2. a plurality of openings in said partition acoustically coupling said active region and tuning chamber for damping said hi h frequency sounds.

2. In a muffler according to claim 1, said passage comprising a rear turnaround passage spaced rearwardly from the front end of said housing, said baffle means partitioning said housing to provide a front turnaround passage adjacent said front end; said pair of conduit sections including an inlet sec tion and a return' section, said inlet section extending rearwardly into said housing through said front end and front turnaround passage to said rear turnaround passage, said return section connecting said rear and front'turnaround passages, said exhaust conduit means also including an exhaust section communicating'with said front turnaround passage and ex-' tending rearwardly therefrom through said rear turnaround passage and the rear end of said housing. I

3. In the combination according to claim 2, said inlet and return sections opening into said rear turnaroundpassage at locations adjacent and spaced from the opposite lateral interior walls of said housing to efiect'said' comparatively unused space at the opposite sides of said housing.

4. In the combination according to'claim 3, said partition cooperating 'withsaid baffle means to define a volume containing the openings of saidinle't and return sections into said rear turnaround passage.

5. 1n the combination according to claim 2, said inlet and return sectionsex'tending withinfsaid, housing adjacent and spaced from opposite interior lateral walls thereof respectively, said exhaust section extending within said housing between said inlet and return sections, said means'for attenuating comparatively high frequency sounds also including 1. a' second partition within said front turnaround passage defining a second tuning chamber separated from the primary flow of 'exhaust gases in said frontturna'round passage between the openings thereinto' of said return and exhaust conduit sections,'and 2. a second plurality of openings in said second partition acoustically'coupling said second tuning chamber and the'region of said-frontturnaround passage employedfor said primary flow of'exhaust gases.

6. In a muffleraccording 'to claim 1, said passage comprising a front turnaround passage, said exhaust conduit means including an inlet section extending rearwardly into said'housing through said front turnaround passage, said pair of conduit sections including a return section means connecting said inlet and return section, the latter opening into said passage to discharge exhaust gases thereinto, said pair of conduit sections also including'an exhaust section opening into said front turnaround passage to receive said exhaust gases therefrom and extending rearwardly through said housing.

7. In the combination according to claim 6, said partition cooperating with said bafflerneans to'define a volume containing the openings of said return and exhaust sections into said front turnaround passage. i

8'. In the combinationaccording to claim 7, said inlet and return sections extending within said housing at laterally spaced locations, said exhaust section extending within said housing between said inlet and return sections. 

1. In a sound attenuating muffler for the exhaust gases of an internal combustion engine, A. an outer housing, B. baffle means partitioning said housing to provide a gas flow turnaround passage therein, C. exhaust conduit means cooperable with said passage for conducting said gases through said housing comprising a pair of conduit sections opening into said passage at spaced locations, at least one of said conduit sections opening into said passage at a location spaced from the interior of said housing to provide a space proximate said interior comparatively unused for conducting said gases through said housing, and D. means for attenuating comparatively high frequency sounds in said gases comprising:
 1. a partition within said passage separating said comparatively unused space from the flow of said gases within an active region of said passage between the openings of said conduit sections into said passage and cooperating with said interior to define a tuning chamber for said high frequency sounds; and
 2. a plurality of openings in said partition acoustically coupling said active region and tuning chamber for damping said high frequency sounds.
 2. a plurality of openings in said partition acoustically coupling said active region and tuning chamber for damping said high frequency sounds.
 2. In a muffler according to claim 1, said passage comprising a rear turnaround passage spaced rearwardly from the front end of said housing, said baffle means also partitioning said housing to provide a front turnaround passage adjacent said front end, said pair of conduit sections including an inlet section and a return section, said inlet section extending rearwardly into said housing through said front end and front turnaround passage to said rear turnaround passage, said return section connecting said rear and front turnaround passages, said exhaust conduit means also including an exhaust section communicating with said front turnaround passage and extending rearwardly therefrom through said rear turnaround passage and the rear end of said housing.
 3. In the combination according to claim 2, said inlet and return sections opening into said rear turnaround passage at locations adjacent and spaced from the opposite lateral interior walls of said housing to effect said comparatively unused space at the opposite sides of said housing.
 4. In the combination according to claim 3, said partition cooperating with said baffle means to define a volume containing the openings of said inlet and return sections into said rear turnaround passage.
 5. In the combination according to claim 2, said inlet and return sections extending within said housing adjacent and spaced from opposite interior lateral walls thereof respectively, said exhaust section extending within said housing between said inlet and return sections, said means for attenuating comparatively high frequency sounds also including
 1. a second partition within said front turnaround passage defining a second tuning chamber separated from the primary flow of exhaust gases in said front turnaround passage between the openings thereinto of said return and exhaust conduit sections, and
 2. a second plurality of openings in said second partition acoustically coupling said second tuning chamber and the region of said front turnaround passage employed for said primary flow of exhaust gases.
 6. In a muffler according to claim 1, said passage comprising a front turnaround passage, said exhaust conduit means including an inlet section extending rearwardly into said housing through said front turnaround passage, said pair of conduit sections including a return section means connecting said inlet and return section, the latter opening into said passage to discharge exhaust gases thereinto, said pair of conduit sections also including an exhaust sEction opening into said front turnaround passage to receive said exhaust gases therefrom and extending rearwardly through said housing.
 7. In the combination according to claim 6, said partition cooperating with said baffle means to define a volume containing the openings of said return and exhaust sections into said front turnaround passage.
 8. In the combination according to claim 7, said inlet and return sections extending within said housing at laterally spaced locations, said exhaust section extending within said housing between said inlet and return sections. 